Towards a Unified Framework using CPACS for Geometry Management in Aircraft Design

Abstract

The performance requirements for the next generations of airliners are stringent and require invention and design of unconventional configurations departing from the classical Cayley functional decomposition. The break with tradition calls for higher fidelity physicsbased predictions of performance early on in the project. The paper makes the case for a unified, open, data-centric software environment for aircraft design and describes the merge of the CEASIOM conceptual design software package, developed by a number of partners including KTH, with the CPACS formalized data management system developed at DLR. The system provides multi-fidelity and multi-disciplinary analysis capabilities for concurrent design by geographically distributed expert teams. The data-centric architecture uses the CPACS schema and access mechanisms for management of design data across all disciplines and fidelity levels. This makes the system extensible and mitigates the problems encountered in handing over the model to later design phases. The concepts have been tested by interfacing external modules to CEASIOM/CPACS through a graphical CPACS XML editor, the ACbuilder gateway. Results of comparative analyses on models imported in this way from the RDS and VAMPzero conceptual design packages are reported here. CPACS will be released to the general public in spring '12. The CEASIOM team experience of joining forces via CPACS with DLR is altogether positive and further in-house development of software for aircraft performance prediction and design by the CEASIOM team will use the CPACS system. I. Introduction & Overview A. Classical Conceptual-Preliminary DesignPresent trends in aircraft design towards lighter more flexible airframes flying expanded flight envelopes with augmented stability call for more tightly-coupled multi-disciplinary design procedures to efficiently evaluate the flying qualities of the aero-servo-elastic aircraft. Numerous textbooks 1-4 explain in detail how the entire aircraft design process can be categorized into three distinct phases, each with its own distinct objectives and tasks: (1) conceptual definition at the aircraft level; (2) preliminary definition of its components; and (3), detailed definition for flight. The tools and how they are used, and even the people using them, usually change between the phases.Conceptual design is primarily a search process to formulate a set of design variable quantities, which, according to appropriate modeling principles, define a vehicle that fulfills a set of minimum requirements determined by its mission. The tools for the search are provided by mathematical modeling (usually empirically based) to find a quantified description of the aircraft concept and its size, weight, and performance. The first step sizes the aircraft, i.e calculates the aircraft takeoff gross weight, empty weight and fuel weight so that it achieves the range called for in the design specification. This results in a quantification of design parameters that determine the aircraft configuration involvin...

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